Dual plasma deposition of Ag-Cu metal incorporated diamond-like carbon coatings: Structural, electrochemical, and antibacterial properties

Diamond-like carbon (DLC)/Ag, DLC/Cu, and DLC/AgCu films were deposited on stainless steel 316 (SS316) substrates using a sequential dual plasma system i.e. plasma-enhanced chemical vapor deposition (PECVD) and sputtering. A DLC as base layer was first deposited by PECVD, followed by the surface deposition of Ag and Cu through sputtering. The effects of Ag and Cu incorporation were investigated by varying deposition time. Film thickness, morphology, composition, and structure of films were analyzed by profilometer, Raman spectroscopy, FESEM-EDS, and X-ray diffraction (XRD), respectively. Surface wettability, mechanical properties, and electrochemical corrosion of films were evaluated using water contact angle, microhardness and potentiodynamic polarization tests, while antibacterial activity against Staphylococcus aureus InaCC B4 was examined by calculating the CFU/mL. The deposited films on SS316 were confirmed through surface and cross-section observation. DLC/Cu films showed improved hardness, while DLC/Ag films exhibited improved hydrophobic properties with contact angle at 111.9 ± 3.4°. The degree of crystallinity of films was found at 69.2% for DLC/Ag, 36.3% for DLC/Cu, and 51.4% for DLC/AgCu. Electrochemical corrosion tests revealed the highest anti-corrosion performance through charge transfer resistance on DLC/AgCu films. Furthermore, the results of antibacterial showed DLC/AgCu films completely inhibited bacterial growth (CFU ≈ 0). This study suggests that DLC/AgCu coatings have potential for antibacterial and corrosion-resistant for biomedical applications.